Beat-by-beat validation of ECG gating

Area of Science:

• Cardiology
• Nuclear Medicine
• Biomedical Engineering

Background:

• Accurate assessment of left-ventricular (LV) function is crucial for diagnosing and managing cardiac diseases.
• R-wave-gated time-activity curves (TACs) derived from nonimaging detector systems are increasingly used for LV function analysis.

Purpose of the Study:

• To compare LV function parameters derived from individual cardiac cycles with those obtained from R-wave-gated LV TACs.
• To quantify potential systematic underestimates in LV function parameters derived from gated LV TACs.

Main Methods:

• Utilized an ultra-high-efficiency nonimaging detector system to analyze 512 cardiac cycles per patient (n=30).
• Measured ejection fraction, peak ejection and filling rates, and their timing relative to the R-wave.
• Compared averaged individual cycle measurements with values derived from R-wave-gated LV TACs.

Main Results:

• A small, detectable systematic underestimate was observed in some LV function parameters derived from gated LV TACs.
• The underestimate was smaller and less variable for systolic parameters (≤8% in any patient) than for diastolic parameters (≤20% in any patient).
• Most patients exhibited values within acceptable limits, but a subset required beat-length windowing for diastolic parameters.

Conclusions:

• LV function measurements from gated TACs generally reflect true average values adequately.
• Beat-length windowing may be necessary for precise diastolic parameter assessment in specific patient groups.
• The accuracy of gated LV TACs for systolic parameters is robust, with minimal underestimation.